Question 1

Assume you had a function named update() that updates shared data. Illustrate how a mutex lock named mutex might be used to prevent a race condition in update().

Accepted Answer

void update()
{
mute...

Question 2

Semaphores and mutex locks both provide mutual exclusion.

Accepted Answer

A) True 
 B)False

Question 3

Mutex locks and counting semaphores are essentially the same thing.

Accepted Answer

A) True 
 B)False

Question 4

Which of the following is not true about test_and_set instruction?

Accepted Answer

A)   It is a hardware instruction
B)   It is executed atomically
C)   Returns the original value of passed parameter
D)   Returns the new value of passed parameter
E)   Set the new value of passed parameter to "TRUE"F) A) and E)
G) B) and D)

Question 5

Which of the following is true?

Accepted Answer

A)   No deadlock implies no starvation;
B)   No starvation implies no deadlock;
C)   Deadlock doesn't imply starvation;
D)   Starvation implies deadlock.E) A) and B)
F) None of the above

Question 6

Explain two general approaches to handle critical sections in operating systems.

Accepted Answer

Critical sections may use preemptive or ...

Question 7

Which of the following is NOT true for Peterson's solution?

Accepted Answer

A)   Mutual exclusion is preserved
B)   The progress requirement is satisfied
C)   The bounded-waiting requirement is met
D)   Peterson's solution works for synchronization among more than two processesE) All of the above
F) C) and D)

Question 8

The preemptive kernel may be more responsive than non-preemptive kernel.

Accepted Answer

A) True 
 B)False

Question 9

Semaphore implementation overcomes the busy waiting problem.

Accepted Answer

A) True 
 B)False

Question 10

In _________, the process requests permission to access and modify variables shared with others.

Accepted Answer

A)   entry section
B)   critical section
C)   exit section
D)   remainder sectionE) C) and D)
F) All of the above

Question 11

Which of the following statements is true?

Accepted Answer

A)   A counting semaphore can never be used as a binary semaphore.
B)   A binary semaphore can never be used as a counting semaphore.
C)   Spinlocks can be used to prevent busy waiting in the implementation of semaphore.
D)   Counting semaphores can be used to control access to a resource with a finite number of instances.E) A) and D)
F) All of the above

Question 12

In _________, the process may be changing common variables, updating a table, writing a file, and so on.

Accepted Answer

A)   entry section
B)   critical section
C)   exit section
D)   remainder sectionE) A) and C)
F) A) and B)

Question 13

When mutex lock is implemented as a binary semaphore, what should its value be initialized to be?

Accepted Answer

A)   0
B)   1
C)   -1
D)   none of the aboveE) C) and D)
F) All of the above

Question 14

Which of the following is not true about compare_and_swap instruction?

Accepted Answer

A)   It is a hardware instruction
B)   It is executed atomically 
C)   Returns the original value of passed parameter
D)   Set the new value of passed parameter to "TRUE"
E)   Set the variable "value" the value of the passed parameter "new_value" but only if "value" =="expected"F) A) and C)
G) A) and B)

Question 15

What is the correct order of operations for protecting a critical section using a binary semaphore?

Accepted Answer

A)   release()  followed by acquire() 
B)   acquire()  followed by release() 
C)   wait()  followed by signal() 
D)   signal()  followed by wait() E) A) and C)
F) All of the above

Question 16

What is the difference between semaphore and mutex lock?

Accepted Answer

Semaphores are similar to mutex lock in ...

Question 17

Which of the following regarding mutex lock is NOT true?

Accepted Answer

A)   mutex lock is a hardware solution to critical-section problem
B)   mutex lock is a higher-level software solution to critical-section problem
C)   mutex lock suffers from busy waiting
D)   the general rule of thumb is to use a mutex lock if the lock will be held for a duration less than two context switchesE) C) and D)
F) A) and B)

Question 18

Explain what race condition is.

Accepted Answer

A situation where several processes acce...

Question 19

Explain what busy waiting is.

Accepted Answer

While a process is in its critical secti...

Question 20

Under which of the following contention loads does traditional synchronization become faster than CAS-based synchronization?

Accepted Answer

A)   uncontended
B)   moderate contention
C)   high contention
D)   none of the aboveE) A) and B)
F) A) and C)

Exam 6: Synchronization Tools

Which of the following is not true about compare_and_swap instruction?

Correct AnswerverifiedShow Answer

Semaphores and mutex locks both provide mutual exclusion.

Correct AnswerverifiedShow Answer

The preemptive kernel may be more responsive than non-preemptive kernel.

Correct AnswerverifiedShow Answer

In _________, the process requests permission to access and modify variables shared with others.

Correct AnswerverifiedShow Answer

Semaphore implementation overcomes the busy waiting problem.

Correct AnswerverifiedShow Answer

When mutex lock is implemented as a binary semaphore, what should its value be initialized to be?

Correct AnswerverifiedShow Answer

Assume you had a function named update() that updates shared data. Illustrate how a mutex lock named mutex might be used to prevent a race condition in update().

Correct Answerverifiedvoid update(){mute...View AnswerShow Answer

Which of the following is true?

Correct AnswerverifiedShow Answer

Explain what busy waiting is.

Correct AnswerverifiedWhile a process is in its critical secti...View AnswerShow Answer

Which of the following statements is true?

Correct AnswerverifiedShow Answer

Mutex locks and counting semaphores are essentially the same thing.

Correct AnswerverifiedShow Answer

In _________, the process may be changing common variables, updating a table, writing a file, and so on.

Correct AnswerverifiedShow Answer

Which of the following is not true about test_and_set instruction?

Correct AnswerverifiedShow Answer

What is the correct order of operations for protecting a critical section using a binary semaphore?

Correct AnswerverifiedShow Answer

What is the difference between semaphore and mutex lock?

Correct AnswerverifiedSemaphores are similar to mutex lock in ...View AnswerShow Answer

Which of the following regarding mutex lock is NOT true?

Correct AnswerverifiedShow Answer

Explain two general approaches to handle critical sections in operating systems.

Correct AnswerverifiedCritical sections may use preemptive or ...View AnswerShow Answer

Under which of the following contention loads does traditional synchronization become faster than CAS-based synchronization?

Correct AnswerverifiedShow Answer

Explain what race condition is.

Correct AnswerverifiedA situation where several processes acce...View AnswerShow Answer

Which of the following is NOT true for Peterson's solution?

Correct AnswerverifiedShow Answer

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void update()
{
mute...
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While a process is in its critical secti...
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Correct Answer
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Semaphores are similar to mutex lock in ...
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Critical sections may use preemptive or ...
View Answer

Correct Answer
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Correct Answer
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A situation where several processes acce...
View Answer

Correct Answer
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